Topical drug delivery systems are known. These systems deliver drugs, therapeutic agents and other desired substances transdermally and may be designed to act locally at the point of application or to act systemically once entering the body's blood circulation. In these systems, delivery may be achieved by means such as direct topical application of a substance or drug in the form of an ointment or the like, or by adhesion of a patch with a reservoir or the like that holds the drug and releases it to the skin in a time-controlled fashion.
Transdermal delivery systems for agents such as drugs, pain relieving compounds, vitamins, and skin improving compounds have been in use for a number of years. These transdermal delivery systems using creams have been developed for use with analgesics and skin refining compounds. Transdermal systems using a patch have been developed for nicotine and estrogen therapies, for instance, estradiol technology described in U.S. Pat. No. 6,521,250 to Meconi, et al.
While effective for their purpose, these systems have typically only been useful for transdermal delivery of relatively small molecules. The skin's porous structure permits such small molecules to pass from the epidermis to the dermis via diffusion. However, large molecules, such as insulin, are not able to diffuse through the skin and cannot be delivered by these known means. One such solution has been provided in U.S. patent application Ser. No. 10/448,632 filed on May 30, 2003 to Perricone, the disclosure of which is incorporated herein by reference.
While the delivery of large molecules such as insulin have been addressed, such systems do not address the storage and retention of the effectiveness of the drug to be delivered. Many pharmaceuticals and biologically active compounds, such as insulin, must be kept cool and away from heat to remain effective and prevent denaturing at ambient temperatures. Such substances may not be stored or carried (without refrigeration) by the user. Often drugs like insulin must be administered throughout the day and should be in ready-access to or carried by the user, which may expose the compound to high temperatures. As such, there remains a need to stabilize compositions, including insulin, so that they are resistant to warmer temperatures and have a longer life at these temperatures without a need for refrigeration